Resist performance for the negative tone develop organic development process

ABSTRACT

A process and composition for negative tone development comprises providing a photoresist film that generates acidic sites. Irradiating the photoresist film patternwise provides an irradiated film having exposed and unexposed regions where the exposed regions comprise imaged sites. Baking the irradiated film at elevated temperatures produces a baked-irradiated film comprising the imaged sites which after irradiating, baking, or both irradiating and baking comprise acidic imaged sites. Treating the baked-irradiated film with a liquid, gaseous or vaporous weakly basic compound converts the acidic imaged sites to a base treated film having chemically modified acidic imaged sites. Applying a solvent developer substantially dissolves regions of the film that have not been exposed to the radiant energy, where the solvent developer comprises a substantial non-solvent for the chemically modified acidic imaged sites. One-step simultaneous base treatment and solvent development employs a composition comprising a mix of the basic compound and solvent developer.

RELATED APPLICATIONS

This application is a Non-Provisional application based on and claimingpriority from Provisional Application 61/760,451, filed Feb. 4, 2013,which is incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The field of the invention comprises improved processes and compositionsfor negative tone development employing a non-aqueous developer toproduce high resolution negative-tone images using a photoresist.

BACKGROUND OF THE INVENTION

The realization of advanced lithographic technology beyond the 14 nmnode requires the implementation of patterning materials and processeswith ultimate performance in order to cope with intrinsicallycontrast-limited exposure tools. The reduction in imaging wavelengthfrom the long-standing 193 nm ArF Lithography (DUV) to the expected 13.5nm Extreme Ultraviolet Lithography (EUV) will improve the resolvingpower of ultimate optical systems used by the semiconductor industry,and is expected to enable the extension of Moore's Law to the 10 nm nodeand beyond.

The optical resolving power of ArF and EUV scanners can only be realizedas a material pattern formed on a semiconductor substrate if the spatialresolution of the imaging material is commensurate to the quality of thedelivered aerial image. At the same time, the imaging layer is requiredto carry acceptable sensitivity to the imaging wavelength and providelow line-width roughness (LWR), good adhesion to the underlyingsubstrate and large post apply bake (PAB) and post exposure bake (PEB)latitude. Chemically amplified resists have become the workhorse of thelithographic industry due to the ability to satisfy the aforementionedrequirements in a sustainable manner across multiple technology nodes.

Utilizing chemically-amplified (CA) resists is typically consideredwithin the context of positive-tone resist imaging and development,where the exposed regions of a photoresist are removed by an aqueousbasic developer (tetraalkylammonium hydroxide (TMAH)) after apost-exposure bake (PEB) step, while the unexposed regions remaininsoluble. This is referred to as positive-tone development (PTD).

One way to reverse the tone of a chemically amplified resist originallydesigned to be developed in the positive tone with aqueous basedeveloper is to utilize an organic developer that removes the unexposedportion of the resist film, while the exposed regions remain unaffected.This process is known as negative-tone development (NTD) and has foundextensive applications in the area of 193 nm double patterning usingbright field masks, particularly in the case of small feature openingssuch as contact hole and trench patterning. Hereinafter, NTD will beused to refer exclusively to refer to the use of organic solvents asdevelopers to produce negative-tone images.

The resist contrast of the NTD process is determined by the solubilitydifferences between the relatively nonpolar unexposed resist and themore polar resist material that is generated in the exposed regions ofthe film. As mentioned previously, in the NTD process the organicsolvent dissolves the unexposed areas, and creates a negative image ofthe exposed chemically amplified photoresist. Processing of a chemicallyamplified resist in a NTD fashion utilizing anisole as the organicsolvent developer was first reported by J. G. Maltabes, S. J. Holmes, J.R. Morrow, R. L. Barr, M. Hakey, G. Reynolds, W. R. Brunsvold, C. G.Wilison, N. Clecak, S. MacDonald, and H. Ito, 1× Deep UV LithographyWith Chemical Amplification for 1-Micron DRAM Production, SPIE Vol.1262, Advances in Resist Technology and Processing VII (1990), pp. 2-7.

There are a number of limitations, however, with the industrialapplication of NTD. Due to toxicological, environmental, and especiallyflammability issues there are a limited number of organic solvents thatare compatible with semiconductor manufacturing. This is a seriousimpediment to finding the optimum developing solvent for a given resist.At this time it appears there are less than 6 organic solvents that areusable on fabrication development tracks.

Current high performance resists are highly optimized for development inaqueous TMAH developer. Many positive-tone resists perform poorly innegative tone development. Some don't work at all, and many functionalresists exhibit significant defect, profile and film thinning problemsin the exposed areas. Radical changes in the photoresist chemistry toimprove NTD performance in acceptable NTD developing solvents wouldrequire extensive work to match the positive-tone performance that hasbeen optimized over the last three decades.

There exists a need in the industry for a generalized process to improvethe NTD performance of a CA resist developed with organic solvent toprovide a negative tone image. The detailed materials and process toaccomplish this will be disclosed below.

SUMMARY OF THE INVENTION

The present invention comprises compositions, structures, articles ofmanufacture, processes and products produced by the processes thataddress the foregoing needs, and provides improved negative tonedevelopment (NTD) performance to produce a high resolution negative toneimage in a photoresist using an organic solvent developer, i.e., a NTDsolvent.

The invention in one embodiment comprises treating a photoresist (afterexposure and optional post exposure bake but prior to organic solventdevelopment) by contacting the imaged resist film with a basic compoundthat converts the organic acidic species comprising the latent chemicalimage into one of reduced solubility in organic solvent developer.

This treatment of the resist to improve NTD performance can be carriedout in several ways.

The exposed and baked resist may be treated with a solution of anaqueous dilute base, i.e., a basic compound, such that none of theexposed film is dissolved but sufficient base penetrates the film so asto increase the resist contrast in the subsequent NTD process. Withoutbeing bound by any theory, it is presumed that the improvement is theresult of generation of ionic species in the imaged features due to theinteraction of the basic compound with the pendant acidic groups in theexposed photoresist material.

We employ Bronsted bases as the basic compound, e.g., both ionicBronsted bases and non-ionic Bronsted bases both of which are known inthe art. Bronsted bases include N-bases, e.g. nitrogen compoundscomprising ammonia, hydroxyl amine, or an organic nitrogen compound. Wecan employ the nitrogen compound as a solution. In one example, weemploy the organic nitrogen compound as a dilute aqueous solution, suchas a dilute aqueous solution of TMAH. The Bronsted bases or basiccompound also comprises metal based compounds that include monovalent ormultivalent metal ions. We also use the metal based compounds insolution based on solvents comprising water or mixtures of water withorganic solvents, e.g., polar organic solvents, and combinationsthereof. Non-ionic organic Bronsted bases may comprise N-bases such asphosphazenes, e.g., BTPP, P₁-t-Bu, BEMP, BEMP on PS, P₁-t-Oct, P₂Et,P₂-t-Bu, P₂-t-Bu on PS, P₂—F, P₄-t-Bu, P₄-t-Oct, and P₅—F, respectivelySigma-Aldrich Product #'s 79432, 445363, 360007, 536490, 79412, 420425,79416, 71477, 52585, 79421, 79422 and 87652, and their art-knownequivalents and combinations thereof.

Hydroxides or art-known organic acid salts or other salts of Group IA,or Group IIA metals, Lanthanides or zinc or other metals can be used asthe metal based compound. In one embodiment the organic acids used toform these salts comprise the lower molecular weight organic acids,e.g., those having up to about 8 carbon atoms such as formic or aceticacid, as well as propionic acid, butyric acid, pentanoic acid, hexanoicacid, heptanoic acid, octanoic acid, and the like and the isomersthereof, and combinations thereof. The other salts that may be formedwith these metals comprise the nitrogen acid salts, such as salts formedby reacting these metals with nitric, nitrous, or hyponitrous acid andcombinations thereof.

Group IA and Group IIA metals used in this regard comprise, e.g.,lithium, potassium, sodium and calcium, as well as zinc or theLanthanides and other metal ions that are known to bind to weakly acidicexchange resins. Multivalent ions based on amines or metals such as zincor lanthanum are particularly useful as they could potentially formcrosslinked polymer salt networks potentially improving resist contrast.

In a second embodiment, the exposed resist can also be treated with avapor or a gas comprising ammonia, hydroxyl amine, an organic amine,e.g., a monovalent or multivalent organic amine to create metal freesalts that improve resist contrast when developed with organic solvents.If solutions of ammonia, hydroxyl amine, a monovalent or multivalentorganic amine are employed they can be comprised of carrier organicsolvents, such as polar organic solvents, water or mixtures thereof.Examples of suitable carrier organic solvents are the lower alkanols,e.g., those having up to about 8 carbon atoms, which are substantiallynon solvents for the resist, such as methanol, and ethanol, as well aspropanol, butanol, pentanol, hexanol, heptanol, octanol and the like andthe isomers thereof, and combinations thereof. The role of the carriersolvent is to act as a transport solvent for the basic compound to beincorporated into the resist film.

In a third embodiment, instead of a basic compound treatment prior toNTD development, as described in the first and second embodiments, thebasic compound (e.g., Bronsted base) is combined directly with the NTDsolvent to allow for a one step development process. In this single stepNTD process we select the organic NTD solvent and the Bronsted base sothat a chemical polarity change can occur in the exposed acidic sitesfaster than the rate of film dissolution and development and increaseimproved contrast and performance. We use the Bronsted bases incombination with or dissolved in substantially anhydrous solventscomprising polar organic solvents such as the lower alkanols describedherein or NTD solvents also described herein and their equivalents, orcombinations of these lower alkanols and NTD solvents.

Other additives (e.g. surfactants) known in the art to improve thetransport of the basic species into the resist film can also be employedin any of the processes described above, either in aqueous or polarorganic solvents.

The contrast curves and images shown in the drawings illustrate theinvention. Some of these contrast curves reflect the results ofexperiments in which we exposed a model resist and fully formulatedresists by rinsing them with dilute aqueous base solution and thendeveloped in the indicated solvents. Another contrast curve illustratesthe process of the invention using an anhydrous solution of an organicNTD solvent with a dissolved Bronsted base such that the salt-formationprocess occurs during the NTD process itself.

By using the processes and compositions of the present invention, animprovement in NTD patterning performance can be achieved for materialsthat are not compatible with the organic development process.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings set out the invention, and are included toillustrate various embodiments of the invention, and together with thisspecification also serve to explain the principles of the invention.These drawings comprise various Figures that illustrate a process toimprove the patterning performance of a photoresist in negative tonedevelopment to produce a high resolution negative tone image in aphotoresist.

FIGS. 1-12 comprise contrast curves and photomicrographs of photoresistfilms treated according to the process of the present invention, i.e.,

FIG. 1 A illustrates PBOCST (poly(tert-butoxyoxycarbonylstyrene))contrast curves at 248 nm exposure (KrF) illustrating standard NTD, andtwo examples of the inventive process;

FIG. 1B illustrates PBOCST contrast curves at 248 nm exposure (KrF)illustrating use of the inventive process with different hydroxidesalts;

FIG. 2 illustrates contrast curves at 248 nm (KrF) of KRS-XE with andwithout pre-rinse with dilute TMAH prior to NTD with methyl benzoate(MeB);

FIG. 3A and FIG. 3B illustrate 150 nm nested lines/space patterns ofKRS-XE exposed with 248 nm DUV light (KrF), FIG. 3A showing methylbenzoate NTD process and FIG. 3B the inventive process comprising arinse with 0.0065N TMAH prior to development with methyl benzoate;

FIG. 4 illustrates contrast curves at 248 nm (KrF) of experimentalresist using a standard methyl benzoate (MeB) NTD process and inventiveprocesses comprising a pre-rinse with 0.002N TMAH solution prior to NTD;

FIG. 5 illustrates contrast curves at 248 nm (KrF) of experimentalresist A using a standard 2-heptanone NTD process and inventiveprocesses comprising a pre-rinse with 0.002N TMAH solution prior to NTD;

FIG. 6A to FIG. 6D illustrates 140 nm features (140 nm lines/140 nmspaces) of experimental resist exposed with 248 nm DUV (KrF),m with FIG.6A a comparison of PTD using 0.26N TMAH, FIG. 6B NTD using methylbenzoate, FIG. 6C inventive process using 0.002N TMAH rinse then NTDusing methyl benzoate, and FIG. 6 D inventive process with intermediateDI water rinse;

FIG. 7 illustrates EUV contrast curves of experimental resist using NTDdeveloper methyl benzoate and inventive process with 0.0016N TMAH rinseprior to NTD with methyl benzoate;

FIG. 8A and FIG. 8B illustrate 22 nm features by EUV imaging of anexperimental resist, developed as shown in FIG. 8A with standard methylbenzoate NTD develop (dose 11.2 mJ/cm²), and FIG. 8B using the processdescribed in this invention: 0.002N TMAH rinse, DI-water rinse, and thenmethyl benzoate NTD develop (dose 12 mJ/cm²);

FIG. 9A and FIG. 9B illustrate e-beam exposure of 25 nm half pitch (HP)features (25 nm lines/25 nm spaces) of an experimental e-beam resist at,(FIG. 9A) 39 μC/cm², and (FIG. 9B) 42 μC/cm² using the process asdescribed of this invention;

FIG. 10 illustrates contrast curves of commercial 193 nm resist at 193nm (ArF) exposure using NTD developer n-butyl acetate (NBA) andinventive process with 0.000325N TMAH rinse prior to NTD with n-butylacetate;

FIG. 11 illustrates commercial resist exposed ax 248 nm and developed in2-Heptanone/4M2P (1:5 ratio) with different tetraalkyi ammoniumhydroxides. Increased NTD contrast and reduced top loss when using NTDsolvent with added tetraalkl ammonium hydroxides. Increased NTD contrastand reduced top loss when using NTD solvent with added tetraalkylammonium hydroxide;

FIG. 12 illustrates contrast curves of commercial 193 nm resist at 193nm (ArF) exposure using NTD developer n-butyl acetate (NBA) andinventive process with vapor phase treatment using ammonium hydroxideprior to NTD with n-butyl acetate.

DETAILED DESCRIPTION OF THE INVENTION

To achieve the foregoing and other advantages, and in accordance withthe purpose of this invention as embodied and broadly described herein,the following detailed description comprises disclosed examples of theinvention that can be embodied in various forms.

The specific processes, compounds, compositions, and structural detailsset out herein not only comprise a basis for the claims and a basis forteaching one skilled in the art to employ the present invention in anynovel and useful way, but also provide a description of how to make anduse this invention. The written description, claims, abstract of thedisclosure, and the drawings that follow set forth various features,objectives, and advantages of the invention and how they may be realizedand obtained. These features, objectives, and advantages will alsobecome apparent by practicing the invention.

The invention in one aspect comprises using inorganic or organicBronsted bases to treat exposed photoresist films prior to negative-tonedevelopment with an organic solvent. Without being bound by any theory,the generation or formation of ionic species or counterions (e.g. salts)in the exposed areas of the chemically amplified photoresist filmimproves the patterning performance (e.g. resist contrast) in organicsolvent developers used in NTD. In particular, typical photoresistscomprise polymer-bound acidic groups in the exposed regions afterexposure and an optional post exposure bake (PEB) either or both ofwhich result in acidolysis of protecting groups (such as tertiary estersor acetals). Converting these resist-bound acidic groups into ionicspecies (e.g. salts) through their reaction with a Bronsted base rendersthe photoresist significantly less soluble in the organic solventdeveloper than the exposed photoresist itself thus improving the resistcontrast.

In one embodiment, the inventive process comprises an improved processof producing negative-tone photoresist pattern using a photoresistdeveloped with an organic solvent developer comprising the steps of:

(a) providing a photoresist film that can be processed to generateacidic sites;

(b) irradiating the photoresist film with radiant energy to provide anirradiated film having exposed and unexposed regions in said film, theexposed regions comprising imaged sites;

(c) optionally baking the irradiated film at elevated temperatures toproduce a baked irradiated film comprising the imaged sites;

(d) the imaged sites comprise acidic sites formed after irradiating orboth irradiating and baking;

(e) contacting the irradiated film with a basic compound, withoutdissolving the film, to form a base treated film;

(f) Optionally rinsing the base treated film in water or other solvent;

(g) developing the treated film with an organic solvent developer thatsubstantially dissolves regions of the film that have not been exposedto the radiant energy to produce a negative-tone image.

We previously described the basic compound and noted the use of alcoholsas carrier solvents is determined by their solubility in water. Weselect alcohols in this regard from (but are not limited to) thoselisted below which also includes their solubility in water (inparentheses) at 20 degrees Celsius:

-   -   Methanol (miscible), ethanol (miscible), 1-propanol (miscible),        2-propanol (miscible), 2-methyl-1-propanol (87 g/liter),        1-butanol (8.3 g/liter), 2-butanol (200 g/liter), tert-butanol        (miscible), 1-pentanol (22 g/liter), 2-pentanol (45 g/liter),        3-pentanol (59 g/liter), 2-methyl-2-butanol (120 g/liter),        2-methyl-1-butanol (31 g/liter), 3-methyl-1-butanol (28        g/liter), 3-methyl-2-butanol (59 g/liter), cyclopentanol (36        g/liter), cyclohexanol, 1-hexanol (5.9 g/liter),        2-ethyl-1-butanol (10 g/liter), 2-methyl-1-pentanol (8.1        g/liter), 2-methyl-2-pentanol (33 g/liter), 2-methyl-3-pentanol        (20 g/liter), 3-methyl-2-pentanol (19 g/liter),        3-methyl-3-pentanol (45 g/liter), 4-methyl-1-pentanol (7.6        g/liter), 4-methyl-2-pentanol (15 g/liter), 1-heptanol (0.1        g/liter) and 1-octanol (0.3 g/liter).

Importantly the basic compound must not dissolve the underlying resist,but only act as a carrier of basic species to be incorporated into theresist film.

The applicability of organic or inorganic Bronsted bases is determinedby their basicity, as well as their solubility in the carrier solvent iforganic solvents, e.g., polar organic solvents, water, or their mixturesare employed.

In general, the organic amine bases employed according to the inventioncomprise N-bases, e.g., compounds having the formulae RNH₂, RR′NH,RR′R″N, and RR′R″R′″ N⁺X⁻, where R, R′, R″, and R′″ are the same ordifferent organo substituents, or organo substituents that can be joinedtogether, and X⁻ may comprise OH⁻ a halogen or other art-knownquaternary ammonium cationic species. These bases may also compriseheterocyclic nitrogen compounds known in the art, some of which wedescribe herein.

In particular, quaternary ammonium salts, such as thetetraorganoammonium hydroxide salts R₄N⁺OH⁻, where R can be an alkylgroup having up to about 18 carbon atoms or an aromatic group includinglower alkyl substituted aromatic groups having up to about ten carbonatoms or combinations of both of such alkyl and aromatic groups, areparticularly useful in the present invention. The OH⁻ anion of thesesalts alternatively can be any quaternary ammonium anion known in theart such as those used in the examples of the present invention as wellas other known anions which we select so as not to interfere with thefunction of the substrate or wafer on which the process is used (e.g.,microelectronic devices [MEMS] such as a semiconductor, and the like).Combinations of these salts may also be used in the invention.

As noted, cations of Group IA metals and Group IIA metals can be used asthe counterion, as well as other multivalent metals, e.g., Zn and theLanthanides such as La, or the other Lanthanide metals (i.e., metalshaving atomic numbers 58 to 71). The metal salt or metal hydroxidesolution of these metals would have to be compatible with themicroelectronic sub-structures already present in the semiconductorwafer in a way that the metal ions or anions should not introduceunwanted doping or poisoning in the existing semiconductor devices orother microelectronic devices or other substrates the invention is usedon. The same criteria apply for nitrogen compounds such as ammonia andthe amines used according to the invention.

The polyvalent inorganic bases as well as any polyvalent organicnitrogen compounds described herein can enter into cross-linkingreactions (e.g., via salt bridges) with the deprotected photoresistwhich provides another benefit to the process of the invention.

Some nitrogen-containing Bronsted bases useful according to theinvention can be selected from (but are not limited to): hydroxylaminesknown in the art such as N-Methyl hydroxylamine hydrochloride andhydroxyl amine as well as, methylamine, ethylamine, dimethylamine,propylamine, trimethylamine, 1,3-propanediamine, 1,2,3-triaminopropane,pyrrolidine, morpholine, piperidine, n-butylamine, tert-butylamine,diethylamine, 1,4-butanediamine, piperidine, n-pentylamine,diethylmethylamine, cyclohexylamine, n-hexylamine, triethylamine,benzylamine, aniline, imidazole, pyrazole, and ethylenediamine. Itshould be understood that a wide variety of basic nitrogen compound maybe used in this invention. Amines are further described by Morrison andBoyd, ORGANIC CHEMISTRY Second Edition, (1966), Chapter 22 et seq. whichalso lists at pp. 720-721, some amines that can be selected for use inthe present invention.

The concentration of the Bronsted base in solution can vary from about0.00001N to about 0.23N or about 0.00001N to about 0.01N. and thecontact time on the substrate can vary from about 1 second to about 5minutes depending on concentration of the Bronstead base and thetreatment process employed. Preferably, the contact time is less than120 seconds. Subsequent organic solvent development can also vary overthese time spans, with the objective being to adjust concentrations andexposure times sufficiently to obtain the desired performance.

When treating the deprotected or exposed resist films with gaseous orvaporous solutions of non-metallic Bronsted bases according to theinvention, we use solutions of these bases at elevated temperatures atatmospheric, sub atmospheric or super atmospheric pressures, where thetemperature of the Bronsted bases or solutions thereof is sufficientlyhigh to convert the liquidus phase to the gaseous or vaporous phase, butnot above a temperature that would adversely affect the Bronsted bases,photoresist or the substrate on which we apply the photoresist. Thepressures employed in this regard comprise from about 0.1 atmosphere toabout 10 atmospheres, and the time of treatment adjusted tosubstantially react the areas of deprotected photo resist with thecounterions. We conduct the sub atmospheric and super atmosphericprocesses in an autoclave.

In another aspect of the invention some suitable organic solvents or NTDsolvents for the NTD portion of the present invention comprise solventshaving a carbonyl or ether group such as for example Methyl benzoate(MeB), Ethyl 3-ethoxypropionate (EEP), 2-Heptanone (MAK),4-Methyl-2-pentanone (4M2P), N-butyl acetate (NBA), Anisole,Acetophenone, their equivalents, and combinations thereof.

In a second embodiment, the inventive process comprises a process ofproducing negative-tone photoresist pattern using a photoresistdeveloped with an organic solvent developer comprising the steps of:

(a) providing a photoresist film that can be processed to generateacidic sites;

(b) irradiating the photoresist film with radiant energy to provide anirradiated film having exposed and unexposed regions in the film, theexposed regions comprising imaged sites;

(c) optionally baking the irradiated film at elevated temperatures toproduce a baked irradiated film comprising the imaged sites:

(d) the imaged sites comprise acidic sites formed after the irradiatingor both the irradiating and the baking;

(e) contacting the irradiated film with a basic compound, withoutdissolving said film, to form a base treated film (the basic compoundmay be in the gaseous or vaporous phase);

(f) developing the treated film with an organic solvent developer topreferentially remove regions of the film that have not been exposed tothe radiant energy to produce a negative-tone image.

In a third embodiment, we employ a one-step process in which the NTDdeveloper comprises a mix, i.e., a combination of the organic NTDsolvent described herein and a basic compound described herein such thatthe polarity improvement occurs during the NTD process itself. In thisone-step process, the organic NTD solvent and the basic compound, in oneembodiment, are selected so that change in polarity (due to the basiccompound) of exposed regions occurs before film dissolution anddevelopment.

Suitable photoresist films for the inventive processes described hereinthat can be processed to generate acidic sites are well known in theart, such as those based on polyhydroxystyrene (PHOST) or acrylicpolymers (e.g., photoresists based on acrylate or methacrylatefunctionality), and those containing moieties comprised of alicyclicgroups or heterocyclic groups containing oxygen, fluorine, nitrogen orsulfur atoms. A wide variety of suitable photoresists have beendescribed by H. Ito Chemical Amplification Resists for Microlithography,Adv. Polvm. Sci. 2005, 172, 37-245.

The photoresist may also be comprised of condensation polymers ofphenolic compounds (e.g., novolacs), which are the reaction products ofan aldehyde such as acetaldehyde or formaldehyde, and a phenol such asphenol itself, or phenol substituted with 1 or 2 alkyl groups of 1 toabout 9 carbon atoms each, e.g., o-, m-, and p-cresol, the xylenols,p-tert-butyl phenol, and p-nonylphenol, p-phenyl-phenol, resorcinol,bis(4-hydroxyphenyl)methane, and bis(4-hydroxyphenyl)2-propane, orpoly(norbornene)-co-maleic anhydride polymers.

A key ingredient of the photo resist compositions used in practicing theinvention comprises the so-called photochemical acid generator (PAG) andusually take the form of iodonium (R₂I⁺X⁻) or sulfonium (R₃S⁺X⁻) salts,where X is a halogen, e.g., chlorine. These compounds decompose uponlight exposure to provide a complicated combination of products, chiefamong which is the acid HX. This acid then catalyzes the deprotectionreaction that removes the protecting group on the photoresist compounds,such as the organooxycarbonyloxy or ketal groups on the hydroxylatedstyrene polymers described herein. Ohasi et al., United States PatentPublication No. 20080008965, paragraphs [0095] to [0117] describe PAGs.Okeda et al. et al., United States Patent Publication No. 20070146887,paragraphs [0953] to also describe PAGs. The photoacid generator may bebound to the photoresist material, preferably through the anion. Theseresists are referred to as polymer-bound PAG photoresists and have beencommonly used for EUV lithography.

The radiant energy source can be any one of UV, DUV, EUV, or electronbeam energy. The invention can also be used with exposures comprisingvisible light. The radiant energy can be generated with a laser based onthe rare gasses listed in Group VIIIA of the Periodic Table of theElements, e.g., He, Ne, Ar, Kr, or Xe. Although Rn is a rare gas, it isavoided because of its radioactivity. Excimers of the rare gasses,sometimes referred to as exiplexes are also suitable, such as thehalogen eximers, e.g., fluorine excimers, such as ArF and KrF.

The substrate may also comprise an anti-reflective coating, an organicplanarizing layer, a hardmask, a dielectric layer, a metal layer andother art-known substrates in the field of microelectronics. After thenegative-tone process, the resist pattern may be transferred into theunderlying substrate using an etch process such as reactive ion etching,chemical etching, and the like.

To illustrate the inventive processes, several examples withaccompanying Figures are described. The lithographic benefits of usingthe inventive processes described herein are shown by observing changesin contrast curves and patterning performance. A contrast curve is agraph showing resist thickness (y-axis or ordinate) as a function ofdose (x-axis or abscissa). A contrast curve gives information aboutresist behavior, i.e., which exposure dose (energy) is needed to changethe resist solubility in a developer between soluble and insoluble, andresist contrast, referring to the dose range over which this solubilityswitch will happen (a larger difference in dissolution rate over anarrower dose range indicating higher contrast). The contrast curve mayalso give information about thickness loss (known as toploss orthickness retention) and potential profile issues like footing or scum(due to incomplete dissolution of the interfacial resist region incontact with the underlying film). The term “chemical contrast” alsoknown as “latent image” is the resist film thickness post-exposure andthe optional post-exposure bake (PEB), but prior to development. Thechemical contrast shows the resist shrinkage due to chemical changes(e.g. volatilization of protecting groups) in the resist film.

In the following examples the resists are all spin coated on top ofsilicon wafers pre-coated with 63 nm DUV-42P bottom anti-reflectivecoating (BARC) from Brewer Science unless otherwise stated. To createthe contrast curves, the resists are exposed to create an array of openfield exposures with varying exposure doses, processed according togiven procedure, and the film thickness of each exposure field measuredusing a NanoSpec 6100 tabletop film analysis system as function of dose.Doses are measured in millijoules per square centimeter (mJ/cm²) for 248nm, 193 nm and EUV exposures, and in microcoulombs per square centimeter(μC/cm²) for e-beam exposures. All post-application bakes andpost-exposure bakes were for 60 seconds unless otherwise indicated.Line-space resist patterns for 248 nm were exposed using a chrome onglass (COG) darkfield mask unless otherwise indicated. All features wereimaged using a scanning electron microscope (SEM).

Example 1A

Four silicon wafers were spincoated with 140 nm of a positive-tone modelphotoresist formulated from Poly(tert-butoxycarbonylstyrene) (PBOCST)(molecular weight of 15,000 grams per mole (g/mol)) and 5 weight percentof Triphenylsulfonium perfluorobutanesulfonate (TPS—N) in PropyleneGlycol Methyl Ether Acetate (PGMEA). After spincoating, the wafers werepost-apply baked (PAB) at 110° C. and exposed in a dose array with a 248nm (KrF) stepper and thereafter subjected to a post-expose bake (PEB) at120° C. The four wafers were individually processed in four differentways:

Wafer 1) Develop in 0.26N tetramethylammonium hydroxide (TMAH) for 30seconds and rinsed in water 10 seconds—Standard positive-tonedevelopment (PTD) for reference;

Wafer 2) Develop in methyl benzoate (MeB) for 30 seconds—Standardnegative tone development (NTD) for reference;

Wafer 3) Rinse with 0.0065N TMAH for 30 seconds and dry prior todevelopment in methyl benzoate (MeB) for 30 seconds;

Wafer 4) Rinse with 0.0065N TMAH for 30 seconds and dry prior todevelopment in ethyl 3-ethoxypropionate (EEP) for 30 seconds.

Contrast curves of the wafers 2-4 are shown in FIG. 1A. Thepositive-tone contrast curve for wafer 1 was omitted for clarity. Asshown in FIG. 1A, PBOCST dissolves at all doses in common NTD developersMeB and EEP (EEP not shown in Figure) indicating it is not compatiblewith standard NTD processes. In contrast, a rinse with aqueous 0.0065NTMAH rinse solution (wafers 3 and 4, this invention) prior to NTDrenders the resist insoluble to the organic solvent developer at acertain exposure dose thereby creating a high contrast negative toneresist pattern.

Example 1B

Three silicon wafers were prepared with a positive-tone PBOCSTformulation as described in Example 1A. After PEB, the three wafers wereprocessed in three different ways:

Wafer 1) Rinse with 0.0065N TMAH for 30 seconds and dry prior todevelopment in methyl benzoate (MeB) for 30 seconds;

Wafer 2) Rinse with 0.0065N lithium hydroxide (LiOH) for 30 seconds anddry prior to development in methyl benzoate (MeB) for 30 seconds;

Wafer 3) Rinse with 0.0065N sodium hydroxide (NaOH) for 30 seconds anddry prior to development in methyl benzoate (MeB) for 30 seconds.

Contrast curves for the three wafers in Example 1B are shown in FIG. 1B.Here three dilute hydroxide solutions with different cations (TMAH, LiOHand NaOH) are used in the inventive process. Without rinse the resistwould fully dissolve in methyl benzoate at all doses (as shown in FIG.1A).

Examples 2-10 (and FIGS. 2-10) similarly illustrate that the rinsecompositions and process of the present invention clearly change thedissolution properties of the exposed photoresist in NTD solventenabling the originally positive-tone photoresist to exhibit highcontrast in NTD processes.

Example 2

Three wafers were spin coated with a KRS-XE, a ketal protectedpoly(hydroxystyrene) positive-tone photoresist, and baked at PAB=90° C.giving a film thickness of 190 nm. The coated wafers were exposed in adose array with a 248 nm (KrF) stepper and thereafter baked at PEB=90°C. The three wafers were processed in three different ways:

Wafer 1) Develop in 0.26N TMAH for 30 seconds and rinsed in water 10seconds—Standard positive-tone development (PTD) for reference;

Wafer 2) Develop in methyl benzoate (MeB) for 30 seconds, standardnegative tone development (NTD) for reference;

Wafer 3) Rinse with 0.0065N TMAH for 30 seconds and dry prior todevelopment in methyl benzoate (MeB) for 30 seconds.

Contrast curves of the three wafers in Example 2 are shown in FIG. 2.Development with 0.26N TMAH developer results in standard positive-tonebehavior for KRS-XE, for reference. However, the common NTD developerMeB dissolves the KRS-XE resist at all doses. A rinse with 0.0065N TMAHsolution prior to organic solvent development renders the resistinsoluble to the organic solvent developer at a certain exposure dosethereby creating a high contrast negative tone resist pattern.

Example 3

Two wafers were spin coated with positive-tone KRS-XE photoresist andbaked at PAB=90° C. giving a film thickness of 190 nm. The coated waferswere patternwise exposed with a 248 nm (KrF) stepper and baked at aPEB=90° C. The two wafers were processed in two different ways:

Wafer 1) Develop in methyl benzoate (MeB) for 30 seconds, standardnegative tone development (NTD) for reference;

Wafer 2) Rinse with 0.0065N TMAH solution for 30 seconds and dry priorto development in methyl benzoate (MeB) for 30 seconds.

SEM images of the two wafers are illustrated in FIG. 3 with 150 nmfeatures (150 nm line/150 nm space). FIG. 3A shows the methyl benzoateNTD process and FIG. 3B) using the process disclosed in this invention:rinse of the resist with 0.0065N TMAH solution prior to development withmethyl benzoate. An improvement in patterning performance is observedusing this post-exposure rinse process prior to development in NTDdeveloper.

Example 4

Three wafers were spin coated with an experimental positive-tone resist(EB-P3247 from Shin-Etsu Chemical) and baked at PAB=110° C. giving afilm thickness of 80 nm. The coated wafers were exposed with a dosearray using a 248 nm (KrF) stepper and thereafter baked at PEB=90° C.The three wafers were processed in three different ways:

Wafer 1) Develop in methyl benzoate (MeB) for 30 seconds, standardnegative tone development (NTD) for reference;

Wafer 2) Rinse with 0.0065N TMAH for 30 seconds and dry prior todevelopment in methyl benzoate (MeB) for 30 seconds;

Wafer 3) Rinse with 0.0065N TMAH for 30 seconds, dry and a subsequentrinse with deionized water (DI) for 5 seconds and dry again prior todevelopment in Methyl benzoate (MeB) for 30 seconds.

Contrast curves of the three wafers are shown in FIG. 4. The standardNTD process using methyl benzoate results in significant resist toploss(bad thickness retention). In contrast, using the inventive processcomprising a rinse with 0.002N TMAH solution prior to development in NTDsolvent substantially eliminates this toploss. It should be noted thatthe treatment with the dilute 0.002N TMAH solution produces minimalthickness changes compared to chemical contrast (solid thick line). Inaddition, by including a water rinse after treatment with the 0.002NTMAH solution and prior to the organic solvent development provides ameans for optional profile control.

Example 5

Similar to Example 4, three wafers were spin coated with an experimentalpositive-tone resist EB-P3247 (Shin-Etsu Chemical) and baked at PAB=110°C. giving a film thickness of 80 nm. The coated wafers were exposed in adose array using a 248 nm (KrF) stepper and thereafter baked at PEB=110°C. The three wafers were processed in three different ways:

Wafer 1) Develop in 2-heptanone for 30 seconds, standard negative tonedevelopment (NTD) for reference;

Wafer 2) Rinse with 0.0065N TMAH for 30 seconds and dry prior todevelopment in 2-heptanone for 30 seconds;

Wafer 3) Rinse with 0.0065N TMAH for 30 seconds, dry and a subsequentrinse with deionized water (DI) for 5 seconds and dry again prior todevelopment in 2-heptanone for 30 seconds.

Contrast curves of the three wafers are shown in FIG. 5. Similarly toExample 4 where methyl benzoate was used, this example shows that resistperformance using 2-heptanone as a NTD solvent also benefits strongly bya rinse with 0.002N TMAH solution prior to development in NTD solvent.In addition, by including a water rinse after the 0.002 N TMAH rinse,contrast strength can be changed and provide a means for optionalprofile control.

Example 6

Four wafers were spin coated with an experimental positive-tone resistEB-P3247 (Shin-Etsu Chemical) and baked at PAB=110° C. giving a filmthickness of 100 nm. The coated wafers were patternwise exposed with a248 nm (KrF) stepper and baked at a PEB=110° C. The four wafers wereprocessed in four different ways:

Wafer 1) Develop in 0.26N TMAH for 30 seconds and rinsed in water 10seconds—standard positive-tone development (PTD) for reference. N.B.,brightfield exposure mask;

Wafer 2) Develop in methyl benzoate for 30 seconds, standard negativetone development (NTD);

Wafer 3) Rinse with 0.0065N TMAH rinse solution for 30 seconds and dryprior to development in methyl benzoate (MeB) for 30 seconds;

Wafer 4) Rinse with 0.0065N TMAH for 30 seconds, dry and subsequentrinse with deionized water (DI) for 5 seconds and dry again prior todevelopment in methyl benzoate for 30 seconds.

SEM images of the four wafers are illustrated in FIG. 6 with 140 nmfeatures (140 nm line/140 nm space). The SEM images shows a side-by-sidecomparison of lithographic patterning performance of A) PTD using 0.26NTMAH developer, B) NTD using methyl benzoate, C) 0.002N TMAH rinse priorto NTD using methyl benzoate and D) 0.002N TMAH rinse with subsequentwater rinse prior to NTD using methyl benzoate.

Example 7

Three wafers were spin coated with a positive-tone experimentalphotoresist EB-P3247 (Shin-Etsu Chemical) and baked at PAB=110° C.giving a film thickness of 70 nm. The coated wafers were exposed in adose array with an Extreme ultraviolet (EUV) exposure tool at LawrenceBerkeley National Lab (LBNL) and baked at PEB=110° C. The three waferswere processed in three different ways:

Wafer 1) Develop in 0.26N TMAH for 30 seconds and rinsed in water 10seconds—Standard positive-tone development (PTD) for reference;

Wafer 2) Develop in methyl benzoate (MeB) for 30 seconds, standardnegative tone development (NTD) for reference;

Wafer 3) Rinse with 0.0016N TMAH rinse solution for 30 seconds and dryprior to development in methyl benzoate (MeB) for 30 seconds.

EUV contrast curves for wafers 2 and 3 in Example 7 are shown in FIG. 7.The positive-tone contrast curve for wafer 1 was omitted for clarity.The rinse process using 0.0016N TMAH prior to NTD with methyl benzoatereduces the resist toploss (thickness loss). This experiment shows theversatility that the described rinse process can also be beneficial inEUV exposures.

Example 8

Two wafers were spin coated with an experimental positive-tone resistEB-P3247 (Shin-Etsu Chemical) and baked at PAB=110° C. giving a filmthickness of 50 nm. The coated wafers were patternwise exposed with anEUV exposure tool at LBNL and baked at a PEB=110° C. The two wafers wereprocessed as follows:

Wafer 1) Develop in methyl benzoate for 30 seconds, standard negativetone development (NTD);

Wafer 2) Rinsed in 0.002N TMAH rinse solution for 30 seconds and dryprior to rinse in DI-water for 5 seconds and dry again prior todevelopment in methyl benzoate for 30 seconds (invention).

SEM images of the resulting resist patterns of Example 8 are pictured inFIG. 8 with 22 nm feature size (22 nm line/22 nm space). A) standard NTDin methyl benzoate, dose 11.2 mJ/cm2 and B) using process described inthis invention: rinse with 0.002N TMAH solution followed by a DI-waterrinse then development with methyl benzoate, dose 12 mJ/cm2. Improvementis observed using the TMAH rinse solution.

Example 9

A wafer was spin coated with an experimental positive-tone resistEB-P3247 (Shin-Etsu Chemical) and baked at PAB=110° C. giving a filmthickness of 50 nm. The coated wafers were patternwise exposed with aVistec Leica VB6 100 KeV e-beam exposure tool and baked at a PEB=110° C.The wafer was processed as follows:

Wafer 1) Rinse in 0.002N TMAH rinse solution for 30 seconds, dry andsubsequent rinse with deionized water (DI) for 5 seconds and dry againprior to development in methyl benzoate for 30 seconds according to theprocess of the present invention.

SEM images of resulting resist patterns of Example 9 are illustrated inFIG. 9 with 25 nm half-pitch (HP) features (25 nm line/25 nm space). TheSEM images shows the good lithographic patterning performance obtainedusing the process described in this invention: 0.002N TMAH rinsesolution followed by DI-water rinse and NTD using methyl benzoate, at 39uC/cm² and 42 uC/cm² exposure dose respectively.

Example 10

Two wafers were spin coated with a positive-tone commercial 193 nmphotoresist AR2073J (JSR Micro, Inc.), and baked at PAB=110° C. giving afilm thickness of 140 nm. The coated wafers were exposed in a dose arraywith a 193 nm (ArF) stepper and thereafter baked at PEB=110° C. The twowafers were processed in two different ways:

Wafer 1) Develop in n-butyl acetate (NBA) for 30 seconds, standardnegative tone development (NTD) for reference;

Wafer 2) Rinse with 0.000325N TMAH for 30 seconds and dry prior todevelopment in n-butyl acetate (NBA) for 30 seconds.

The rinse process using 0.000325N TMAH prior to NTD with n-butyl acetate(NBA) boosts the contrast and reduces the resist toploss (thicknessloss). This experiment shows the versatility that the described rinseprocess can also be beneficial in 193 nm exposures and yet for anotherstandard type NTD solvent, NBA.

A similar experiment (not shown) with the same resist material wascarried out using a 1 Molar (M) Zn(OAc)₂ aqueous rinse prior to NTDusing methyl benzoate. Again, the Zn(OAc)₂ rinse process resulted inless resist toploss and higher contrast after NTD as opposed to thestandard NTD process using methyl benzoate.

Example 11

Two wafers were spin coated with a positive-tone commercial 193 nmphotoresist AR2073J-14 (JSR Micro, Inc.), and baked at PAB=110° C.giving a film thickness of 175 nm. The coated wafers were exposed in adose array with a 193 nm (ArF) stepper and thereafter baked at PEB=110°C. The two wafers were processed in two different ways:

-   Wafer 1) Develop in n-butyl acetate (NBA) for 30 seconds, standard    negative tone development (NTD) for reference;-   Wafer 2) Vapor phase treatment for 30 seconds in saturated ammonia    (vapor NH₃) prior to development in n-butyl acetate (NBA) for 30    seconds.

The contrast curve results of wafers in Example 12 are shown in FIG. 12.This experiment shows versatility that the described invention can alsobe beneficial using vapor phase treatment for improved contrast andreduced toploss.

Example 12

Five silicon wafers were prepared with a positive-tone commercial EUVphotoresist, SEVR-139 (Shin-Etsu Chemical). The resist were spincoatedto a 90 nm film thickness on silicon wafers precoated with AR3 (BARC)from Brewer Science. The resist coated wafers were post-applied baked(PAB) at 110° C. followed by a dose array exposure using a 248 nm (KrF)ministepper and post-expose bake (PEB) at 110° C. The five wafers weredeveloped in different solvents:

Wafer 1) Pure 2-heptanone for 30 seconds; Wafer 2) 0.13N TMAH in4-methyl-2-pentanone (4M2P)/2-heptanone (ratio 5:1 by volume) for 30seconds;

Wafer 3) 0.12 N tetraethylammonium hydroxide (TEAH) in 4M2P/2-heptanone5:1 (ratio 5:1 by volume) for 30 seconds;

Wafer 4) 0.19N butyltrimethylammonium hydroxide (BTMAH) in4M2P/2-heptanone (ratio 5:1 by volume) for 30 seconds;

Wafer 5) 0.26N TMAH for 30 seconds and rinsed in water for 10seconds—standard positive-tone development (PTD) for reference.

The contrast curve results of wafers 1-4 in Example 12 are shown in FIG.11. The positive-tone contrast curve for wafer 5 was omitted forclarity. It can be seen that using this one-step procedure with atetraalkylammonium hydroxide-containing organic developer, absence offooting (i.e., clean dissolution of the interfacial resist region incontact with the underlying film), and reduced top loss (thicknessloss).

Good contrast was obtained for base concentrations ranging from about0.12 mol/dm³ to about 0.19 mol/dm³ for solvent blends of2-heptanone/4M2P. A wide range of base concentrations comprises about0.07N to about 0.23N or a range falling within these limits comprisingabout 0.12 mol/dm³ to about 0.19 mol/dm³. The solvent blend mass ratio(2-heptanone: 4M2P) comprises about (1:10) to about (1:1) or about (1:7)to about (1:3).

By using the process of the invention a resist that would not functionin a negative-tone development process using known organic solventdevelopers such as MeB NBA or EEP instead can be considered for negativetone applications. Again, FIG. 1 illustrates rinsing apoly(tert-butoxycarbonylstyrene) (PBOCST) photoresist with lowconcentration aqueous TMAH prior to organic solvent development rendersthe resist insoluble to the organic solvent developer at a certainexposure dose thereby creating a high contrast negative tone resist.

The improved contrast illustrated for the model resist seen in FIG. 1can be demonstrated in an imaging system based on similar chemistry withKRS-XE, a ketal protected poly hydroxystyrene, high performance e-beampositive-tone resist that is not functional in a common NTD solvent suchas MeB. Pre-rinsing the exposed film with 0.0065 N TMAH improved thecontrast and made this a functioning negative tone resist (see FIG. 2).See also 248 nm imaging result in FIG. 3 a and FIG. 3 b where werespectively compare development of KRS-XE without and with the rinse ofthe present invention.

In addition to improving the resist contrast, FIG. 4 shows that therinse can also be employed to minimize or eliminate the film loss inpositive-tone resists that already function as NTD resists.

Examples in FIGS. 4 through 6 demonstrate that a benefit could beachieved by rinsing the resist with DI-water after the dilute TMAH rinsebut before the organic NTD processing step; 248 nm patterns in FIG. 6show reduced toploss and improved adhesion using the intermittentDI-water rinse.

Other examples shown in FIGS. 7 and 8 illustrate the versatility of thedescribed process, which can also be used in EUV exposure and retain thebenefits. Likewise, FIG. 9 illustrates the good results using e-beamexposure and FIG. 10 using 193 nm exposure.

Example 11 illustrates the second embodiment which additionallydemonstrates that a vapor phase treatment prior to NTD (solvent develop)can benefit with improved contrast and reduced toploss.

Finally, FIG. 12 demonstrates a one-step process described in the thirdembodiment, in which improved contrast and reduced thickness loss can beachieved by a modified solvent developer containing tetraalkylammoniumhydroxide.

Broadly, the compounds of the invention described as having an “R” groupor groups or an “organo substituent” or “organo substituents” comprisevarious organic and other moieties and also include organic or othermoieties or substituents that can be further substituted withsubstituents; where these organic or other moieties, and/or substituentscomprise inter alia, alkyl, aryl, halogens, such as fluorine, chlorine,bromine, or iodine, alkyloxy, alkyloxo, aryloxo, alkylcarbonyloxy,carboalkoxy, aryloxy, arylcarbonyloxy, or carboaryloxy group, carbonyl,nitro, cyano, halogen-substituted alkyl or halogen-substituted alkyloxy,substituted alkyl, alkylene, alicyclic, hydrocarbyl, cyclicalkyl(cycloaliphatic), hetero cycloaliphatic, aralkyl or alkaryl, acyl,acyloxy, alkylenoxy, such as defined inter alia by Allen et al., U.S.Pat. No. 7,193,023, col. 3, line 51 to col. 6, line 24, and Mizutani etal. U.S. Pat. No. 7,232,640, col. 8, line 54 to col. 12, line 14, andall other moieties and substituents defined by Allen et al. (supra),and/or Mizutani et al. (supra). For the purpose of this invention, themoieties and/or substituents also include combinations of moietiesand/or substituents, such as two or more of the moieties and/orsubstituents. Allen et al., (supra) and Mizutani et al. (supra) giveranges of carbon atoms that apply to the various substituents and/ormoieties of this invention and the following discussion applies to theseranges as well as the combinations of moieties and/or substituents.

Throughout this specification, and abstract of the disclosure, theinventors have set out equivalents, of various materials as well ascombinations of elements, materials, compounds, compositions,conditions, processes, structures and the like, and even though set outindividually, also include combinations of these equivalents such as thetwo component, three component, or four component combinations, or moreas well as combinations of such equivalent elements, materials,compositions conditions, processes, structures and the like in anyratios or in any manner.

Additionally, the various numerical ranges describing the invention asset forth throughout the specification also includes any combination ofthe lower ends of the ranges with the higher ends of the ranges, and anysingle numerical value, or any single numerical value that will reducethe scope of the lower limits of the range or the scope of the higherlimits of the range, and also includes ranges falling within any ofthese ranges.

The terms “about,” “substantial,” or “substantially” as applied to anyclaim or any parameters herein, such as a numerical value, includingvalues used to describe numerical ranges, means slight variations in theparameter or the meaning ordinarily ascribed to these terms by a personwith ordinary skill in the art. In another embodiment, the terms“about,” “substantial,” or “substantially,” when employed to definenumerical parameter include, e.g., a variation up to five per-cent, tenper-cent, or 15 per-cent, or somewhat higher.

All scientific journal articles and other articles, including internetsites, as well as issued and pending patents that this writtendescription or applicants' Invention Disclosure Statements mention,including the references cited in such scientific journal articles andother articles, including internet sites, and such patents, areincorporated herein by reference in their entirety and for the purposecited in this written description and for all other disclosurescontained in such scientific journal articles and other articles,including internet sites as well as patents and the references cited inany of the foregoing, as all or any one may bear on or apply in whole orin part, not only to the foregoing written description, but also thefollowing claims, abstract of the disclosure, and drawings.

Although the inventors have described their invention by reference tosome embodiments, other embodiments defined by the doctrine ofequivalents are intended to be included as falling within the broadscope and spirit of the foregoing written description, the followingclaims, abstract of the disclosure, and drawings.

1. A process of producing negative-tone photoresist patterns using aphotoresist developed with an organic solvent developer comprising thesteps of: (a) providing a photoresist film that can be processed togenerate acidic sites wherein said photoresist film comprises aphotoresist polymer selected from a polymer having an aromatic ringsubstituted with a group comprising an oxy group, PBOCST, or a phenolicresin; (b) irradiating said photoresist film with radiant energy toprovide an irradiated film having exposed and unexposed regions in saidfilm, said exposed regions comprising imaged sites; (c) optionallybaking said irradiated film at elevated temperatures to produce a bakedirradiated film comprising said imaged sites; (d) said imaged sitescomprise acidic sites formed after said irradiating or both saidirradiating and said baking; (e) contacting said irradiated film with abasic compound, comprising without dissolving said film, to form a basetreated film wherein said basic compound comprises a dilute watersolution or lower alkanol solution of NaOH, KOH, or LiOH, or an organicBronsted base, or an ionic organic Bronsted bases; (f) rinsing said basetreated film in water or other solvent; (g) developing said treated filmwith an organic solvent developer that substantially dissolves regionsof said film that have not been exposed to said radiant energy toproduce a negative-tone image. 2-3. (canceled)
 4. The process of claim 1wherein said basic compound comprises inorganic Bronsted bases.
 5. Theprocess of claim 1 wherein said basic compound comprises an inorganiccompound based on the Group IA metals, Group IIA metals, Zinc or theLanthanides dissolved in a solvent. 6-9. (canceled)
 10. The process ofclaim 9 wherein said quaternary ammonium compound comprises one of TMAH,TEAH, BTMAH, BTEAH, TBAH, HDTMAH, and combinations thereof.
 11. Theprocess of claim 1 wherein said basic compound comprises non-ionicorganic Bronsted N-bases. 12-13. (canceled)
 14. The process of claim 1wherein said photoresist polymer contains esters of carboxylic acidsactive in acidolysis reactions
 15. The process of claim 1 wherein saidphotoresist polymer comprises PBOCST.
 16. The process of claim 1 whereinsaid photoresist polymer comprises a phenolic polymer.
 17. The processof claim 1 wherein said photoresist polymer comprises an acrylicpolymer.
 18. The process of claim 1 wherein said photoresist polymercomprises a poly(norbomene)-co-maleic anhydride polymer.
 19. (canceled)20. A process of producing a negative-tone photoresist pattern using aphotoresist developed with an organic solvent developer comprising thesteps of: (a) providing a photoresist film that can be processed togenerate acidic sites wherein said photoresist film comprises aphotoresist polymer selected from a polymer having an aromatic ringsubstituted with a group comprising an oxy group, PBOCST, or a phenolicresin; (b) irradiating said photoresist film with radiant energy toprovide an irradiated film having exposed and unexposed regions in saidfilm, said exposed regions comprising imaged sites; (c) optionallybaking said irradiated film at elevated temperatures to produce a bakedirradiated film comprising said imaged sites; (d) said imaged sitescomprise acidic sites formed after said irradiating or both saidirradiating and said baking; (e) developing said treated film with asolvent developer comprising an organic solvent developer in combinationwith a basic compound comprising a Bronsted base to preferentiallyremove regions of said film that have not been exposed to said radiantenergy to produce a negative-tone image; wherein said solvent developer,comprises an organic solvent selected from Methyl benzoate,4-Methyl-2-pentanone, N-Butyl acetate, Anisole, Acetophenone andcombinations thereof.
 21. The process of claim 20 wherein saidphotoresist film is on a substrate comprising a wafer.
 22. The processof claim 20 wherein said organic Bronsted bases comprise a quaternaryammonium compound R₄N⁺OH⁻ where R comprises an organo group having from1 up to about 18 carbon atoms comprising an alkyl, aromatic, or alkylsubstituted aromatic group, combinations of said R groups, andcombinations of said quaternary ammonium compounds. 23-24. (canceled)25. The process of claim 20 comprising about 0.12 mol/dm³ to about 0.19mol/dm³ of said basic compound and said solvent developer comprises acombination of 2 solvents in a solvent blend mass ratio of about 1:10 toabout 1:1.
 26. The process of claim 24 comprising about 0.12 mol/dm³ toabout 0.19 mol/dm³ of said basic compound and said solvent developercomprises a combination of 2 solvents in a solvent blend mass ratio ofabout 1:10 to about 1:1.
 27. The process of claim 20 wherein said basiccompound comprises a quaternary ammonium compound of the formula R₄N⁺OH⁻wherein R comprises an organo group having from 1 up to about 18 carbonatoms comprising an alkyl, aromatic, or alkyl substituted aromaticgroup, and combinations of said R groups, and combinations of saidquaternary ammonium compounds.
 28. The process of claim 20 wherein saidbasic compound comprises a quaternary ammonium compound comprising oneof TMAH, TEAH, BTMAH, BTEAH, TBAH, HDTMAH, and combinations thereof. 29.(canceled)
 30. The process of claim 20 wherein said basic compoundcomprises NaOH, KOH, or LiOH.
 31. (canceled)
 32. The process of claim 20wherein said photoresist polymer comprises PBOCST.
 33. The process ofclaim 20 wherein said photoresist polymer comprises a phenolic polymer.34. The process of claim 20 wherein said photoresist polymer comprisesan acrylic polymer.
 35. The process of claim 20 wherein said photoresistpolymer comprises a poly(norbornene)-co-maleic anhydride polymer. 36.(canceled)
 37. The process of claim 20 wherein said the organic solventand said Bronsted base are selected so that a chemical polarity changecan occur in imaged sites comprising said acidic sites at a rate fasterthan the rate of film dissolution and development in order to increasecontrast.
 38. A photoresist article of manufacture comprising aphotoresist polymer having photo generated acidic sites reacted with abasic compound comprising at least one of ammonia, hydroxyl amine, anorganic amine, or a metal based compound and combinations thereof.
 39. Acomposition of matter comprising a photoresist polymer selected from apolymer having an aromatic ring substituted with a group comprising anoxy group, or PBOCST, or a phenolic resin, or a ketal protectedpoly(hydroxystyrene) positive-tone photoresist polymer, and an organicsolvent selected from Methyl benzoate, Ethyl 3-ethoxypropionate,2-Heptanone, 4-Methyl-2-pentanone, N-Butyl acetate, Anisole,Acetophenone and combinations thereof admixed with a basic compoundcomprising a Bronsted base. 40-41. (canceled)
 42. The composition ofclaim 39 wherein said basic compound comprises inorganic Bronsted bases.43. (canceled)
 44. The composition of claim 39 wherein said basiccompound comprises NaOH, KOH, LiOH.
 45. The composition of claim 39wherein said basic compound comprises ionic organic Bronsted bases. 46.The composition of claim 39 wherein said basic compound comprisesnon-ionic organic Bronsted N-bases.
 47. The composition of claim 39wherein said Bronsted bases comprise a quaternary ammonium compoundR₄N⁺OH⁻ where R comprises an organo group having from 1 up to about 18carbon atoms comprising an alkyl, aromatic, or alkyl substitutedaromatic group, combinations of said R groups, and combinations of saidquaternary ammonium compounds, wherein said quaternary ammonium compoundcomprises one of TMAH, TEM, BTMAH, BTEAH, TBAH, HDTMAH, and combinationsthereof.
 48. (canceled)
 49. The composition of claim 39 wherein saidbasic compound comprises polyvalent organic or inorganic Bronsted bases.50. The composition of claim 39 wherein the concentration of saiddeveloper solvent in combination with said base compound comprisesconcentration from about 0.00001 normal to about 0.23 normal.
 51. Thecomposition of claim 39 where the basic compound comprises amines orammonia. 52-53. (canceled)
 54. The composition of claim 39 wherein saidorganic solvent and said basic compound are selected so that saltformation in said film occurs faster than the rate of film dissolutionand development.
 55. The process of claim 24 wherein said photoresistpolymer comprises a polymer having an aromatic ring substituted with agroup comprising an oxy group.
 56. The process of claim 24 wherein saidphotoresist polymer comprises PBOCST.
 57. The process of claim 24wherein said photoresist polymer comprises a ketal protectedpoly(hydroxystyrene) positive-tone photoresist polymer.
 58. The processof claim 24 wherein said photoresist polymer comprises a phenolicpolymer.